Galaxy formation and evolution

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Discovery of a Color-Selected Quasar at z=5.50

(2000)

Authors:

Daniel Stern, Hyron Spinrad, Peter Eisenhardt, Andrew J Bunker, Steve Dawson, SA Stanford, Richard Elston

Near-Infrared-Spectroscopy with Extremely Large Telescopes: Integral-Field- versus Multi-Object-Instruments

ESO Conference and Workshop Proceedings No. 57 57 (2000) 292-299

Authors:

F Eisenhauer, M Tecza, N Thatte, S Mengel, R Hofmann, R Genzel

Abstract:

Integral-field-spectroscopy and multi-object-spectroscopy provide the high multiplex gain required for efficient use of the upcoming generation of extremely large telescopes. We present instrument developments and designs for both concepts, and how these designs can be applied to cryogenic near-infrared instrumentation. Specifically, the fiber-based concept stands out the possibility to expand it to any number of image points, and its modularity predestines it to become the new concept for multi-field-spectroscopy. Which of the three concepts --- integral-field-, multi-object-, or multi-field-spectroscopy --- is best suited for the largest telescopes is discussed considering the size of the objects and their density on the sky.

A Serendipitous Search for High-Redshift Lyman alpha Emission: Two Primeval Galaxy Candidates at z~3

(2000)

Authors:

Curtis Manning, Daniel Stern, Hyron Spinrad, Andrew J Bunker

One-Line Redshifts and Searches for High-Redshift Lyman-Alpha Emission

(2000)

Authors:

Daniel Stern, Andrew J Bunker, Hyron Spinrad, Arjun Dey

Stellar Dynamics and the implications on the merger evolution in NGC6240

ArXiv astro-ph/0001424 (2000)

Authors:

M Tecza, R Genzel, LJ Tacconi, S Anders, LE Tacconi-Garman, N Thatte

Abstract:

We report near-infrared integral field spectroscopy of the luminous merging galaxy NGC 6240. Stellar velocities show that the two K-band peaks separated by 1.6arcsec are the central parts of inclined, rotating disk galaxies with equal mass bulges. The dynamical masses of the nuclei are much larger than the stellar mass derived from the K-band light, implying that the progenitor galaxies were galaxies with massive bulges. The K-band light is dominated by red supergiants formed in the two nuclei in starbursts, triggered ~2x10^7 years ago, possibly by the most recent perigalactic approach. Strong feedback effects of a superwind and supernovae are responsible for a short duration burst (~5x10^6 years) which is already decaying. The two galaxies form a prograde-retrograde rotating system and from the stellar velocity field it seems that one of the two interacting galaxies is subject to a prograde encounter. Between the stellar nuclei is a prominent peak of molecular gas (H_2, CO). The stellar velocity dispersion peaks there indicating that the gas has formed a local, self-gravitating concentration decoupled from the stellar gravitational potential. NGC 6240 has previously been reported to fit the paradigm of an elliptical galaxy formed through the merger of two galaxies. This was based on the near-infrared light distribution which follows a r^1/4-law. Our data cast strong doubt on this conclusion: the system is by far not relaxed, rotation plays an important role, as does self-gravitating gas, and the near-infrared light is dominated by young stars.